Scilab function
Last update : 12/1/2004

pvm_probe - Check if message has arrived.

### Calling Sequence

  `[buffid] = pvm_probe(tid, msgtag)`

### Parameters

- `tid`: integer, task identifier of sending process supplied by the user.
- `msgtag : integer, message tag supplied by the user. msgtag should be`>= 0.
- `buffid`: integer, returning the value of the new active receive buffer identifier. Values less than zero indicate an error.

### Description

`pvm_probe` checks to see if a message with label `msgtag` has arrived from `tid`. If a matching message has arrived `pvm_probe` returns a buffer identifier in `bufid`. This bufid can be used in a pvm_bufinfo call to determine infor- mation about the message such as its source and length.

If the requested message has not arrived, then pvm_probe returns with a 0 in bufid. If some error occurs bufid will be < 0.

A -1 in msgtag or tid matches anything. This allows the user the following options. If tid = -1 and msgtag is defined by the user, then pvm_probe will accept a message from any process which has a matching msgtag. If msgtag = -1 and tid is defined by the user, then pvm_probe will accept any message that is sent from process tid. If tid = -1 and msgtag = -1, then pvm_probe will accept any message from any process.

pvm_probe can be called multiple times to check if a given message has arrived yet. After the message has arrived, pvm_recv must be called before the message can be unpacked into the user's memory using the unpack routines.

For example

    arrived = pvm_probe( tid, msgtag );
    if (arrived >= 0) then [bytes, msgtag, tid, info] = pvm_info(arrived); end

### See Also

`pvm_recv`,